1. Field of the Invention
The present invention relates to a method and apparatus for a plasma process, and is particularly concerned with a method and apparatus for a plasma process which enables a high throughput and good quality control during the manufacture of semiconductor integrated circuit elements.
2. Description of the Prior Art
Miniaturization and increased packing density of semiconductor integrated circuit elements have progressed rapidly in recent years, so that it has become necessary to increase the efficiency of the processes of manufacturing these semiconductor integrated circuit elements, and also improve the throughput and quality control thereof. To cope with all these requirements imposed on current processes of manufacturing semiconductor integrated circuit elements, plasma process techniques have been developed, and are proposed in, for example, Japanese Patent Laid-Open No. 95,630/1982 (1982-6), Japanese Patent Laid-Open No. 128,928/1982 (1982-10), and Japanese Patent Publication No. 34,461/1978 (1978-9).
For example, the plasma-processing technique disclosed in Japanese Patent Laid-Open No. 95,630/1982 concerns the processing of samples one-by-one in a plasma, using a plasma processor provided with a radio-frequency plasma generation means which is a single plasma generation means.
This kind of plasma-processing technique obtained by a radio-frequency plasma from a radio-frequency plasma generation means provides a large self-bias, so that the plasma-processing rate is high and consequently the throughput is high, but heavy electrical damage due to ions in the radio-frequency plasma is unavoidable, and thus there is the problem that it is difficult to keep quality as high as possible.
For example, the plasma-processing technique disclosed in Japanese Patent Laid-Open No. 128,928/1982 uses a plasma processor provided with a reactive plasma-etching means acting in a plasma conveyor system, and a reactive spatter-etching means acting in a parallel-plate system. This process comprises pre-processing a sample (for example, dehydrating or descumming the sample surface) using the reactive plasma-etching means in the plasma conveyor system, subjecting the pre-processed sample to predetermined etching by the reactive spatter-etching means in the parallel-plate system using a radio-frequency plasma, and then post-processing (for example, stripping the sample by the reactive plasma-etching means in the plasma conveyor system which was used for the pre-processing.
However, in this plasma-processing technique, the sample is subjected to a plasma process by only a radio-frequency plasma, so that although the throughput is increased in the same way as in the above conventional technique, a problem still remains concerning the maintaining of a satisfactorily high quality.
Another plasma-processing technique described in Japanese Patent Publication No. 34,461/1978 concerns the processing of samples in a plasma by a plasma processor provided with a microwave plasma generation means which is a single plasma generation means.
This technique of plasma-processing samples in a microwave plasma generating means using a microwave plasma provides only a small self-bias, so that electrical damage due to ions in the microwave plasma is small, and thus quality can be maintained at a high level. However, the plasma-processing rate is low, so that this technique has the problem that the throughput cannot be increased.